It's a fun thing to hold in your hand :)

1. Print using the endlessshell_plated.stl file which has the shell split in half and plated for printing.

I used 10% infill, 0.2mm layers, 2 shells, 120mm/s feed, 200mm/sec travel, 230 degrees. My print weighed 27 grams and came out insanely strong.

I glued mine together with thin CA (Cyanoacrylate aka Super Glue) but I bet acetone would work too.

Created in Tinkercad: https://tinkercad.com/things/evaDMLmS8u8-endless-shell